She was 14 when Massachusetts became the first state to legalize same-sex marriage in 2004.

Three years later, her father was elected governor of the state and she became its 'first daughter'.

Now, Katherine Patrick , the 25-year-old youngest daughter of outgoing Governor Deval Patrick and his wife, Diane, is set to be wed to her long-term girlfriend, Alisha Marie Lemieux.

Gov Patrick, a strong supporter of gay rights who is said to be considering running for president one day, announced his daughter's engagement via his office on Friday, describing it as 'joyful' news.

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Engaged: Katherine Patrick (right) , the 25-year-old daughter of outgoing Massachusetts Governor Deval Patrick and his wife, Diane, is set to be wed to her long-term 21-year-old girlfriend, Alisha Marie Lemieux (left)

Pro-active: Over the past few years, Miss Patrick (pictured, right, with her mother, Diane, and father) has been politically active, helping Democrat Gov Patrick in his reelection campaign both in public and on social media

In a statement, his office said: 'The Governor and Mrs. Patrick joyfully announce the engagement of their daughter Katherine Wintersmith Patrick to Alisha Marie Lemieux of New Bedford.'

Miss Patrick, who is studying for her doctorate in psychology, and Miss Lemieux, a 21-year-old sociology undergraduate, currently live together in the San Francisco Bay area of California.

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They have a pet dog named Cora and were pictured together on a skiing holiday in January 2014.

The date and details of their wedding remain unknown. Miss Patrick, who attends the Wright Institute in Berkeley, came out publicly in 2008, two years after her father was elected governor.

Happy: Gov Patrick, a supporter of gay rights who is said to be considering running for president one day, announced his daughter's engagement, describing it as 'joyful' news. Above, Miss Patrick and Miss Lemieux

At home: Miss Patrick, who is studying for her doctorate in psychology, and Miss Lemieux, an undergraduate, currently live together in the San Francisco Bay area of California. They have a pet dog named Cora (above)

Couple: Miss Patrick and her fiancee smile (left) and pose at a ski resort (right) together in Facebook photos

Over the past few years, she has been politically active, helping Democrat Gov Patrick in his reelection campaign both in public and on social media, MassLive.com reported.

She also endorsed former state representative Carl Sciortino - a Democrat, who is gay - in his 2013 congressional bid, which turned out to be unsuccessful.

Gov Patrick's two-term tenure as head of the executive branch of Massachusetts' state government comes to an end on Thursday when Republican Charlie Baker will be inaugurated.

Last month, father-of-two Gov Patrick was left stunned during his monthly Boston Public Radio phone in when he received a call from an altogether unexpected guest.

Katherine at Christmas: In a statement, Gov Patrick said: 'The Governor and Mrs. Patrick joyfully announce the engagement of their daughter Katherine Wintersmith Patrick to Alisha Marie Lemieux of New Bedford'

Gov Patrick puts his arm around his daughter, Katherine, as he takes part in a gay pride parade in 2008

'Uh, Governor, this is Barack Obama, formerly of Somerville,' the mysterious caller told BPR's Ask The Governor. 'I've got a few complaints about service in and around the neighborhood, but I've moved down South since that time...'

At first, a somewhat bewildered Gov Patrick assumed it was a hoax, responding: 'You're kidding, Mr. President. Who is this impersonator? You're very good. Who is this really?'

But within a few moments, he realised it was in fact the real President of the United States of America, referring to the Boston suburb where Mr Obama lived while studying law at Harvard.

Stunned: Last month, father-of-two Gov Patrick was left stunned during his monthly Boston Public Radio phone in (pictured) when he received a call from an altogether unexpected guest - President Barack Obama

As Massachusetts's first black governor, Gov Patrick - whose daughter, Sarah, 28, married in 2011 and gave birth to a son in 2013 - has been mentioned as a possible future White House contender.

Last year, he said he would 'maybe' consider running for president in the future.

However, he has ruled out a bid in 2016.

Gay marriage was legalized in Massachusetts on May 17, 2004, following a landmark court ruling.